This invention relates to a system for moving the mast of a sailboat from one side to the other side of the hull of the boat while the boat is underway, substantially without changing the attitude of the mast with respect to the boat.
The speed of a sailboat through the water is dependent upon several factors besides the main factor of the force and the direction of the wind in relation to the heading of the boat. For example, the sail area, the waterline length of the hull, the wet surface of the hull, the underwater hull shape, and the stiffness of the boat in the water are all factors involved that relate to sailboat speed, and thus are factors to be considered in the design of a sailboat.
Stiffness, or the resistance of a sailboat to the forces causing it to heel or tip sideways in the water, is one of the main factors in determining the speed of a sailboat. All other factors being equal, a sailboat which is more resistant to heeling over in the water can catch more wind with its sail or can carry more sail in a given wind.
Stiffness in a sailboat usually is controlled by a combination of several design factors. One of these is the ballast or weight placed as low in the hull of the sailboat as possible or under the bottom of the boat. Increasing the ballast of a small light displacement boat usually lowers the center of gravity of the hull and results in increasing the stiffness of the boat. When the wind tilts or heels the boat by creating a sideways force on the sails, the hull of the boat tends to rotate or tilt in the water about its center of gravity. Therefore, increasing the ballast tends to increase the poise of the boat, to resist the rotation of the boat in the water.
Another way of increasing sailboat stiffness is to use a centerboard or keel. The centerboard or keel usually is placed under the centerline of the boat, parallel to the length of the boat, so that, for example, if the mast of the boat is tilted to the right, the centerboard or keel must move to the left. Again, when the boat heels, the centerboard, which is located well below the center of gravity of the boat, resists this rotation by pushing against the water beneath the boat, thus resisting tilting of the boat.
Another way to increase stiffness of a sailboat is to increase the width of the hull since a wider boat provides a broader base for supporting the boat in the water.
When the design of a sailboat is modified so as to increase the stiffness of the boat, as by increasing the hull width, or by increasing the size of a centerboard, or by increasing the ballast, these changes tend to reduce the speed of the boat even though the resulting increased stiffness tends to increase the speed of the boat by holding the mast and sails in a more upright attitude to catch more wind.